Batman Arkham City is now not working, BAC loads, but there is no game on the screen (I can get the menu up and options etc.), task manager indicate it's on and running in the processes list, and Steam say "in-game Batman Arkham City".

NB, I don't remember editing the maps in the editor to get them to run, I'm getting this error, I remember playing Necropolis in solo, now the game keeps crashing during map loads, I have a hunch both games are acting up for some linked reason, damaged gpu who knows...